As lgb noted, @cshalvey is the point of contact for questions like this.
So far as I know, the program is currently being reworked, so I believe there is a freeze on new applications until they are finished doing that. If you want more details you'll have to get them from Colm.

Hey everyone, as per usual, @farmdawgnation is completely correct ;)
We are currently reworking the Ambassador program, but I can assure you everyone who previously applied (or had started training) will be contacted, as well as opening up applications to new applicants. Sorry for the delay! And feel free to reach out to me with any questions you may have, cheers!